Portable magnetic tape recorder



May 4, 1954 N. M. HAYNES 2,677,727

PORTABLE MAGNETIC TAPE RECORDER Filed Dec. 20, 1951 4 Sheets$heet 1INVEN TOR.

mj MW A ORNEY May 4, 1954 N. M. HAYNES 2,677,727

PORTABLE MAGNETIC TAPE RECORDER Filed Dec. 20, 1951 4 Sheets-Sheet 2 4/7"Ti E. {/6 36 3Q 37 89 q 38 Hill 2 nn CH (9 1- E I Q8 1% {08 ll 1 J 2Q:

INVENTOI-Q. x/ A 5 W A TTORN E Y y 4, 1954 7 N. M. HAYNES 2,677,727

PORTABLE MAGNETIC TAPE RECORDER Filed Dec. 20, 1951 4 Sheets-Sheet 3 80l ullUl H af fi 65 66 96 A TTORN E Y May 4, 1954 N. M. HAYNES PORTABLEMAGNETIC TAPE RECORDER 4 Sheets-Sheet 4 Filed Dec. 20, 1951 1. .l H H )7yENTOR. MM BY 2 TTORNEY Patented May 4, 1954 UNITED STATES PORT-ABLEMAGNETIC TAPE RECORDER Nathan M. Haynes, Queens, N. Y.

Application December 20, 1951, Serial No. 262,513

3=Clairns. 1

Thi invention relates to magnetic tape recorders and reproducers andmore particularly to such an apparatus which is conveniently andcompletely portable.

A magnetic tape recorder is a precision instruinent in that the tapemust be driven at constant speeds or the quality of reproduction will beimpaired. In fact, an irregularity of of 1 per cent in tape speed can bedetected and more than that, may render the recording e or perhapsalmost unintelligible. Ac codingiy, most if not all tape recorders whichhave been produced and sold in the past, have been designed to operatein one position so as to insure the required accuracy of tape speed.I'he mechanical structure or" such apparatus has uerally been such thatpositioning of the inent in other than the position for which it vdesigned, disturbed the mechanical operation to such a degree that thetape speed became irregular or its drive even became inoperative.

With the foregoing in mind, I have devised a novel form of portable taperecorder which can operate in any position among other advantages wh chwill appear hereinafter. In fact, the re co r of the instant inventionmay be operated.

- it is being carried by a user as during wall;-

that it may operate even while it is being The recorder oi the instantinvention is prefcrab-1y housed in a carrying case which resembles asmall travelling case or the like. ihe case is provided with a handle,and an operating switch is disposed at a selected point so that theswitch may actuated by the users thumb while his hand is on the handle.The case and enclosed mechanism is such as to enable the recorder to reca conversation or the like while a subject may be unaware that hisconversation is being recorded.

in order that the recorder may serve one of its capabilities, i. e.,that of recording a conversation without the knowledge of the subjectand, event to facilitate the operation of the re der, a microphone isprovided in one end of t- 1e carrying case. Ihe selection of theparticular end of the case to be used for this purpose may be governedby the disposition of the operating switch above mentioned so that auser may hold the case in his right hand, for example, operate theswitch with this thumb, and orient the microphone in the direction ofthe subject all bout the subjects knowledge. However, with or withoutsuch knowledge, the recorder may serve the desired purpose of effectinga recording while the case thereof is closed and reo.. ing a minimum ofattention.

The invention embodies further aspects which considered to be of majorimportance. For example, I have devised a single indicating unit whichperforms three functions. It indicates whether the amplifier is on; itdiscloses when the tape drive has reached proper operating speed; and itfurther indicates when the spring 2,677,727 PATENT OFFICE 2 motor withwhich the apparatus is provided, should be rewound. In a portableapparatus of type, it is most desirable to have single elements performtwo or more functions since such characteristics decrease complexity,weight and cost.

The invention further discloses improved means for insuring constantspeed of the tape drive. Thus, the apparatus includes a governor whichincludes a regulating brake of such design that mechanicalirregularities are minimined, notwithstanding any positioning of theinstrument and the fact that substantially no flywheel is required orused for contributing to the constancy of the speed.

The invention will be further understood from the following descriptionand drawings in which:

Figure l is a perspective view of the apparatus including its carryingcase;

Figure 2 is an enlarged plan view of the top operating panel of theapparatus, the cover of the case having been removed;

Figure 3 is a side elevational View, the side of the case having beenremoved, the view being taken along the lines 3-3 of Figure 2;

Figure i is a top View of the operating openings as taken along thelines l of Figure 3 and partly broken away;

Figure 5 is a cross-sectional view of the governor and associated partsthereof when the motor is not in operation;

Figure 6 is a View similar to Figure 5 but showing the parts when themotor is in operation;

Figure '7 is a cross-sectional view as taken along the li es ll of Figur5;

Figure 8 is a front view of the brake disk partly broken away and takenalong the lines 53-t of Figure 5;

Figure 9 is a cross-sectional View as taken along the lines '9-Q ofFigure 6;

Figure 10 is a fragmentary View illustrating the motor brake and itsexternal control post;

Figure 11 is an enlarged fragmentary View illustrating the brake controlpost in its position of applying the brake;

Figure 12 is a view similar to Figure 11 with the brake control postadjusted so as to permit operation of the motor and driving of the tape;

Figure 13 is a cross-sectional view as taken along the lines l33 ofFigure 2;

Figure la is a cross-sectional view as taken along the lines l ll4 ofFigure 4;

Figure 15 is a view taken along the lines 5-i ii of Figure 14;

Figure 16 is a View taken along the lines iE-i & of Figure 3; and

Figure 17 is a cross-sectional View as taken along the lines ill-Al ofFigure 2.

Referring to Figure l, the apparatus is provided with a housing in theform of case it which may resemble a small travelling case. The c isprovided with a conventional type of carrying handle it and a cover 22which is held to the body as by latches 23. To the right of the handle2| and forwardly thereof is disposed the brake control post 24 so thatit may be conveniently operated by the thumb of the user while his handgrasps the handle 2 i. The case further includes an indicator or pilotlight 25 as well as a microphone 26 set in the forward end of the case.

The top or operating panel of the apparatus is shown in Figure 2, thecover 22 having been removed from the hinges iii. A supply reel 32 isrotatably mounted on the panel 38 as is a driven take-up reel 33. Themagnetic tape 34 is adapted to be recorded upon or played back as ittravels from reel 32 to reel 33. The tape is driven by means of capstan35, a spring actuated pressure wheel 36 normally pressing the tapeagainst the capstan. In its movement, the tape is drawn across the faceof the recording or reproducing head 37, guided by a post Panel alsosupports the control knobs or switches such as switch which prepareshead 3? and the amplifier for either playing or recording, as will beevident to those skilled in the art. Such action is conventional andneed not be illus trated or described in any detail. Switch tilcomprises the conventional on-off and volume control switch while a jack:22 may serve as monitoring means for receiving the plug of a set of earphones or the like.

The apparatus of the instant invention drives the tape through a springwound motor while the amplifier is powered by means of dry batteries.The usual 2 volt cells for heating the tube filaments and a higher voltbattery for the plate supply are provided. The high voltage battery maybe seated in compartment 45 while the 2 volt cells may be enclosedbrackets Qt.

The spring motor 553 may take any desired form. In the form shown, itincludes an internally threaded winding shaft 5i which is adapted to beengaged by a suitable handle, not shown, which engages its threads. Tothe end of shaft Si is secured a Worm gear 52 which engages gear 53 forwinding up the motor. A spring 5% is provided to maintain the worm gearin proper position relative to gear 53.

It is evident that the internal mechanism of the spring motor 59 neednot be described, it being sufiicient to point out that the output forceof the spring motor is transmitted through gear 55 to a pinion gear 55which is keyed to shaft 53'. Likewise keyed to shaft 5'? is the largergear the beveled teeth of which engage the worm teeth 59 to drive shaft6%. Shaft 6% drives the capstan 35 which actuates the tape as was aboveerplained.

It will be understood from the foregoing that some form of control isnecessary for regulating the speed of the spring motor as otherwise itspower would be dissipated in one burst. Accordingly, a centrifugal formof governor is provided which governs or regulates the speed of themotor by applying a braking action thereto when the speed tends tobecome excessive. The governor shaft 65 has worm teeth 55 and is driventhereby by means of a fiber gear 67 which is keyed to drive shaft 68.The governor shaft 65, the governor 68 itself, and its associated partsare best shown in Figures 5 to 9.

The action of the governor 65 is to apply a retarding force on the shaftwhich is, of course, transmitted to the drive shaft to and thence to thespring motor through the gearing described. The construction of thegovernor although broadly conventional, has been modified or improved toa considerable degree so as to better adapt it for the purposes ofactuating the tape drive mechanism with the required precision.

The governor comprises a fixed collar it which is secured to governorshaft 65 as by the bolts '21. Three weights [2 are connected to thecollar it by leaf springs 73. Springs 13 are thin, flexible, resilientspring strips secured to collar 70 by the above mentioned bolt H and tothe weight '12 by bolts 14. Springs 13 further extend along shaft 65 andare connected by bolts 15 to a slid.- able collar iii of the frictionwheel or drum ii. Wheel TI is loosely and slidably supported over shaft15, the action of the governor being to slide the wheel 15 as isconventional in such governor mechanisms.

It will be recognized that the connection of collar 18 to shaft 55 issuch as to effect the rotation of the governor mechanism as the shaft 65is rotated by the main drive shaft 68. Pursuant to the action of suchgovernors, the bolts or weights l2 are thrown outwardly by centrifugalforce through rotation of the shaft 65. The springs 73 then draw thebrake wheel or drum ll inwardly from the position shown in Figure 5 tothat shown in Figure 6.

The spring motor and governor mechanism is provided with a frame housingincluding a top plate from which is suspended a circular brake shoe 8!.Brake shoe (H is provided with an annular groove within which isdisposed suitable brake lining material in the form of an annulus 82,this annular brake lining extending outwardly of the shoe 8|.

The periphery of annular brake lining 82 bears against wheel ll so as toapply a braking action thereto. It will be apparent thatnotwithshtanding the slidable or loose fit of wheel "ii on shaft 65, theaction of applying a braking force to the wheel is to correspondinglyretard the rotation of shaft 65 through the leaf springs and collar 70,which in turn imposes such a load on the drive shaft iii! as to slow upthe rotation thereof and thus control the speed of the capstan or tapedrive member. By such governing action, the drive shaft 68 may beregulated to a speed of about 1 /2" per second, up to any reasonablydesired speed depending upon the quality or fidelity or reproduction,which is desired. It will further be observed that the brake shoe 8: isdisposed within a slot 84 in top plate 8i] which permits a degree ofadjustment of the shoe 8| for predetermining the desired speed. It willbe evident that if the shoe 8! is moved to the right, for example, fromthe position illustrated in Figure a greater speed will be permitted andachieved in that the wheel Tl will have to be drawn further to the rightbefore the governor braking action takes effect.

I have determined that the brake shoe 8i should preferably, but notnecessarily, be constructed in the substantially annular form shown inorder to avoid any tilting or skewing action on wheel 7'1. The annularnature of the brake lining groove and brake lining material 82 is suchas to apply an evenly distributed pressure on wheel or drum ll. This isimportant in eliminating or avoiding irregularities in operation, whichas above mentioned, are of critical significance in tape drivemechanisms. It will be recognized, of course, that the annular groove ofshoe 8! may be interrupted to provide separated or spaced contact pointsas long as the contact points are not limited to one which mightunbalance the wheel ":1. It may further be observed that the weights E2should be greater than ordinarly encountered in governor mechanisms ofthis type, a weight of at least 35 grams for each ballhaving been foundsatisfactory for providing the torque required. have further takenadvantage of the presence of collar it for mounting a smallfiywheel 85on shaft but such flywheel is by nomeans essential to the smoothness ofrotation of shaft 65 or shaft til.

The instant application also discloses an indicator light having aplurality of functions. The indicator light 25 is energized and lightedthrough the wires Bil and ill which are connected to the low voltagebatteries as will hereinafter be described. Thus, wire se is connectedto one terminal of the battery, the other terminal of which may begrounded. Accordingly, if wire M is connected to ground the indicator 25will light, as suming the circuit is otherwise closed. In order toproduce such lighting of indicator 25, a threaded shaft 92 is disposedin a column 93 of the spring motor and governor mechanism frame housing.Electrical insulating material ti l insulates the shaft 92 from theframe housing which may be electrically grounded. A contact arm isconnected to shaft 92. It will be recognized that if wheel ll effectscontact with arm then indicator 2s will light up as above described ifthe circuit is otherwise closed. Such cor act arm 95 is effected whenwheel T! is at or approaching its normal position, i. e., whenuninfiuenced by the centrifugal action of weights if. A head 96 servesto adjust the lateral position of shaft 92 so that the indication maytake efi'ect when desired.

Wire Qi is connected to wire 9? through the amplifier on-off switch 4!so that the circuit to the amplifier unit 98 is open when switch ii isoff. Of course, it is also open if arm 95 does not meet wheel ll. When,however, he switch ii is first turned on, the control post 2 will be inits initial braking position so that the motor is not turning and thegovernor is in its normal position. The apparatus will then be in aposition shown in Figure 5 where the wheel ll is in contact with arm 95and indicator 25 will be lit up to show that the amplifier is on andready for recording. However, it should be understood that recordingshould not be commenced until proper operating speed has been attained.This is indicated as follows:

When the brake control post 2 1 is actuated by the user so as to releasethe brake on shaft 5%, the governor will begin to rotate and soon willwithdraw wheel ll from arm 95. This will disclose to the user that themechanism has reached proper operating speed since at this time theindicator light will be extinguished. Now, the spring motor willfunction so as to rotate the ti! and reel 33 at the proper speed.

Assuming now that the spring motor becomes unwound and requiresrewinding, the wheel ll will gradually move to the left so as to effectcontact with arm $5. It has been found to be preferable, although notnecessary, to make a rear face of wheel Tl irregular so that as itretracts to normal position, it first effects intermittent contact witharm 95 and then makes full and constant contact therewith. By thismeans, when the spring motor is becoming unwound, the light 25 willfirst begin to flicker and will then go on continuously. This. will showthat there is no more power leftv in the spring motor and the tape drivewill therefore cease. When the light begins to flicker, the operatorshould rewind the motor so that any further conversation or othersubject will not be lost. It has been found that by employing the motordescribed in the instant application, the tape drive may continue forfifteen minutes or longer at each winding.

As has been above pointed out, the recorder of the instant invention iscapable of operation in substantially any position. The amplifier unit98 is shock mounted in the housing as by rubber grommets 99 and assumesconventional form in respect to its construction and operation. Theparticular governor action is employed because it operates independentlyof position. In addition, the take up and supply reels are likewisemounted and operated so as to be independent of position.

The brake control on shaft 69 which commences the operation of therecorder will now be described. On drive shaft 65) is mounted a wheelHill which serves both as a pulley and a brake drum. Considering firstits function as a brake drum, it serves to arrest and stop the rotationof drive shaft as when contacted by brake shoe lili. Brake shoe i0! ismounted on the brake angle arm "32 which is slidably supported by boltshi3 operating in slot its. Spring we normally maintains the brake shoeNH out of contact with wheel 100. Accordingly, unless arm 8 32 ispressed inwardly, the drive shaft will rotate so as to actuate the tapeand take up reel.

The brake control post 25 serves to control the brake arm It? so as toapply or release the brake. Control post 24 is slidably disposed in slottilt in the top face iii! of the case 29. Post it is formed with aslanted or bevelled leading end its which effects operating contact witharm W2. Thus, when post Ed is actuated to one ex tremity of slot its asillustrated in Figure 11, the arm 192 will be urged inwardly against theaction of spring 35 so as to apply the brake to wheel its. On the otherhand, when post it is slid in the opposite direction as illustrated inFigure 12, the arm H12 will be drawn by spring i235 out of engagementwith wheel it!) and shaft 65 may be rotated by the spring motor.

It will be noted that reel 33 functions as a take-up reel and is drivenby the spring motor for this purpose. The transmission of power iseffected through wheel i013 which serves as a pulley and is mounted ondrive shaft 60. A belt lid is driven by pulley its and is connected tohub i i l which is secured to the take-up reel shaft H2. Shaft H2extends and operates through a bearing member H3 in panel 36. Shaft H2is formed with a plate il l having a pin I it which engages an openingin reel 33 so as to key the reel to the shaft. Shaft H2 continuesupwardly through the central opening of reel 33 where a spring washerlit and a knurled nut ill firmly secure the reel against accidentaldisplacement. Actuation of pulley H0 thus effects suitable rotation ofreel 33 which then functions to take up any tape which passes thecapstan.

Reel 32 is rotatably connected to panel 3B in essentially the samemanner as that of reel 33 save that a clutch mechanism I20 including aspring 12! is provided. Clutch lZU comprises a slipping clutch whichprovides the necessary resistance to maintain the tape at the righttension regardless of how much tape is on the reel 32. The particularslipping clutch employed may follow that described in my applicationSerial Number 182,809, filed September 1, 1950.

It will be understood that the tape is driven at a, controlled speed bymeans of the capstan 35.

In order to stabilize and assure such controlled speed, a pressure wheel36 is urged against the capstan by means of pivoted linkage E26, thenormal position of such linkage and pressure wheel being against thecapstan as urged by spring I27. Pressure Wheel 36 is provided with anouter rubber sleeve as is conventional.

Briefly, the apparatus of the instant invention may be operated asfollows:

In order to make a recording, the tape will first be disposed on supplyreel 32 and switch 40 will be turned to recording position. The onofiswitch 42 will then be turned to the proper volume and indicator 25 willlight. The ampliher will thereupon heat up to operating condition. If thmotor has not been wound it may now be wound by rotating the internallythreaded winding shaft The brake control post 24 will then be actuatedto release the brake Edi and the spring motor will then drive shaft $5as controlled by the governor mechanism. It will be obvious that thebrake control post 2i need not be on the outside of the apparatus butmay be disposed on the operating panel if desired. As the tape is drivenpast the head 31, it will be recorded upon by the sound waves enteringmicrophone 26 which are applied to the amplifier unit 98 and thence tothe recording head in a conventional manner. The user may employ themonitor plug 42 for monitoring the recording as above explained. At theend of the recording, the brake EH is applied.

When it is desired to play back the recording, the switch 4'0 is turnedto play, the pressure wheel 36 is retracted against the action of spring22? and reel 32 is reversely rotated manually so as to return the tapeto the supply reel. Thereafter, the brake is released from drive shaft$3 to commence such play-back. During either recording or play-back, theindicator light 25 will not only indicate whether the amplifier is firstturned on and when proper operating speed has been attained, but willalso warn the user that the spring motor must be rewound as abovedescribed.

The microphone 2% has been illustrated being disposed in the front wallof the rectangular and slightly elongated case 20 in order that arecording may be made while a user is holding nan-- dle 2! which isparallel to the longitudinal axis of the rectangular case and while histhumb is conveniently available for actuating brake control post 24without requiring or evidencing undue movement of his hand for thispurpose. Post it will be observed, is to the left and forwardly of thehandle to facilitate such actuation by the thumb. Thus, during thenormal carrying of the case, the microphone will be properly orientedfor receiving the subject to be recorded and all the user need do isactuate the post 24 assuming, of course, that the switch 40 is on recordand switch 4! is on. Apart from this particular disposition of themicrophone and brake control post 24 which permits recordings to be madewithout the knowledge of the person being recorded, it will beunderstood that the microphone may take conventional forms if thisfeature is not desired. Thus, the output of a microphone may be fed tothe amplifier through a plug on the panel as is conventional.

It will be understood from the foregoing that the apparatus is securelydisposed and maintained in the case 20 regardless of any orientation orpositioning of the case. Even if the case were to be held upside down,all the parts above described will nevertheless operate since they areindependent of any positioning including, of course, the action of thegovernor, the spring motor and the mounting of the reels and theamplifier unit. As a result, the apparatus may be held by its handle 2|while a conversation is going on or while a statement is being made by asubject being recorded and, though the reels might be turned from whatmay be considered their normal position, the device will neverthelessoperate in the manner above described. If any further secrecy isdesired, it is, of course, possible to remove the indicator 25 to aninside position so that may not be evident when the case is closed.Furthermore, the microphone 26 may be concealed as by screening materialin a manner well understood in the art.

What is claimed is:

l. A portable tape recording apparatus comprising a housing including anamplifier unit, a pair of rotatable reels, a spring motor, a first shaftdriven by said spring motor, a capstan driven by said first shaft foractuating magnetic tape from one reel to the other, a pulley on saidfirst shaft, a belt on said pulley and connected to said other reel fordriving it together with said capstan, a second shaft driven by saidspring motor, a centrifugal governor on said second shaft for regulatingthe speed thereof, and a gear connecting said shafts so as to regulatethe speed of the capstan.

2. An apparatus according to claim 1 and wherein said pulley alsofunctions as a brake drum for arresting operation of said shaft, a brakeshoe for effecting braking action with said pulley, an angle armconnected to said brake shoe, one portion of said arm being slidablysupported relative to said pulley and the other portion of said armperpendicularly depending from said one portion, a spring connected tosaid other portion of said arm for normally urging said brake shoe outof contact with said pulley and a slidable brake control post for actingagainst said other portion of said brake arm against the action of saidspring, said brake control post having a bevelled operating edge foractuating said other portion of said brake arm as said brake controlpost is slid.

3. A portable tape recording apparatus comprising a housing including anamplifier unit, a pair of rotatable reels, a spring motor, a first shaftdriven by said spring motor, a capstan driven by said first shaft foractuating magnetic tape from one reel to the other, means to drive oneof said reels so as to take up the actuated tape, a second shaft drivenby said spring motor, a centrifugal governor on said second shaft forregulating the speed thereof and a gear connecting said shafts so as toregulate the speed of the capstan.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,136,739 Tiffany Apr. 20, 1915 2,442,887 Buemete June 8, 19482,609,457 Thurm Sept. 2, 1952 2,616,982 Gray Nov. 4, 1952 FOREIGNPATENTS Number Country Date 567,152 Great Britain Jan. 31, 1945

